Final answer:
Renewable energy resources, such as solar, wind, water, and geothermal power, are sustainable and unlimited over human time scales. Nonrenewable energy resources will eventually be depleted.
Step-by-step explanation:
Renewable energy resources, such as solar, wind, water, and geothermal power, would not run out and can be replenished over time. These sources are naturally replenished by ongoing natural processes, making them sustainable and unlimited over human time scales.
On the other hand, nonrenewable energy resources like fossil fuels (coal, oil, and natural gas) and nuclear power are finite and will eventually be depleted. These resources take millions of years to form and cannot be replaced as fast as they are consumed.
Therefore, the correct answer is a) Renewable.